Autophagy is a cellular degradation response to starvation
or stress whereby cellular proteins, organelles and cytoplasm are engulfed,
digested and recycled to sustain cellular metabolism.We have investigated the effects of
autophagy on TCA cycle activation using 1-13C-pyruvate DNP 13C-MRS. Autophagy
was induced in three cancer cell lines by starvation, dichloroacetate and
PI103 treatment.A significant
reduction in the rate of labelled [1-13C] pyruvate to lactate exchange (and
unpolarised lactate production) was associated with autophagy, rather than
apoptosis or necrosis.A reduction in
lactate production as measured by DNP 13C-MRS, and unchanged NAD+, may
provide a non-invasive surrogate biomarker of autophagy.